Technical Field
Generally, the present disclosure relates to communication systems. More particularly, the present disclosure relates to a method of directional networking. Specifically, the present disclosure is directed to a method of broadcasting information within a wireless network wherein at least some of the nodes within the system use directional antennas.
Background Information
Directional networking is a set of networking and related protocols using one or more directional antennas may be used (for example) in the implementation of Mobile Ad-hoc Networks (MANET). Directional networking is an approach to network and protocol design that focuses on radio devices using directional antennas, as opposed to omni-directional antennas. Directional networking has become popular in military systems with examples being Future Combat Systems—Communications (FCS-C) and Highband Networking Radio (HNR), but more recently this type of networking has started to find application in commercial systems such as IEEE 802.11 and 802.15.
Directional networking systems are often developed in support of MANET network topologies but can also be applied in other topologies such as point to multi-point (PMP) or even point to point (PTP). Many networking protocols require the ability to broadcast information in certain contexts. The term “broadcasting” is used herein to mean distributing data to all nodes capable of hearing transmissions from all nodes that are sending transmissions. Examples of when broadcasting might be needed include when sending a beacon to support discovery or sharing of routing and scheduling tables.
Currently known directional antenna systems tend to be very inefficient when broadcasting information relative to systems that broadcast with omni-directional antenna. Using an omni-directional antenna, a single transmission will reach all nodes that are within communications range at once. However, with a directional antenna only a subset of nodes within communications range may be reached with a single transmission. Because of this, the broadcast must be broken down into multiple transmissions and repeated so that it will reach all nearby nodes. Depending on node distributions and antenna patterns, this method of broadcasting may take a very long time compared to using omni-directional antenna. While one could include two antennas in the system (an omni-directional antenna and a directional antenna) and then use the directional antenna for unicast information and the omni-directional antenna for broadcast, this is not always feasible.
Other currently known systems use a second system with different system parameters geared for broadcasting in order to coordinate the directional system. An example would be the use of a military “Link 16” radio with omni-directional antennas to share pointing parameters for a direction common data link (CDL) so as to instantiate a CDL link. However it is not always possible to include a second system purely for the purpose of broadcasting information to support a directional networking system.